Sandra Payette and Carl Lagoze have self-archived "Flexible and Extensible Digital Object and Repository Architecture (FEDORA)."
Here's an excerpt:
We describe a digital object and repository architecture for storing and disseminating digital library content. The key features of the architecture are: (1) support for heterogeneous data types; (2) accommodation of new types as they emerge; (3) aggregation of mixed, possibly distributed, data into complex objects; (4) the ability to specify multiple content disseminations of these objects; and (5) the ability to associate rights management schemes with these disseminations. This architecture is being implemented in the context of a broader research project to develop next-generation service modules for a layered digital library architecture.